Variable Reductant Injection Pressure for SCR Aftertreatment
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Solution Overview
Problem
Conventional exhaust aftertreatment systems for internal combustion engines face inefficiencies due to fixed reductant insertion pressures, leading to suboptimal mixing of reductant with exhaust gas, increased deposits, and backpressure, which negatively impact catalytic conversion efficiency.
Innovation Solution
A system and method that adjust the pressure of the reductant insertion into the aftertreatment system using a controller and reductant insertion assembly, allowing for varying pressures based on exhaust gas flow conditions to optimize mixing and reduce deposits, by adjusting the operating parameters of the pump and dosing valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reductant is injected at high pressure to improve mixing with exhaust gas, then mixing efficiency is improved, but reductant deposits on sidewalls increase and backpressure increases
Solution Approach 1:
The patent applies dynamics by making the reductant injection pressure variable rather than fixed. The system continuously adjusts injection pressure based on real-time exhaust gas flow rate measurements, allowing optimal pressure to be maintained across varying operating conditions. This dynamic adjustment prevents both excessive pressure (which causes deposits) and insufficient pressure (which causes poor mixing).
Solution Approach 2:
The patent changes the physical parameter of injection pressure from a constant value to a variable value that adapts to operating conditions. By measuring exhaust gas flow rate and calculating optimal pressure accordingly, the system modifies the pressure parameter to achieve efficient mixing while preventing deposit formation on sidewalls.
2Reliability
If reductant injection pressure is increased to improve catalytic conversion efficiency, then conversion efficiency is improved, but backpressure in the aftertreatment system increases
Solution Approach 1:
The system dynamically adjusts the reductant injection pressure parameter based on exhaust gas flow rate measurements. By calculating optimal pressure as a function of flow rate, the system maintains sufficient pressure for good mixing and catalytic efficiency while avoiding excessive pressure that would create harmful backpressure in the aftertreatment system.
3Device complexity
If fixed reductant injection pressure is used to simplify system design, then device complexity is reduced, but mixing efficiency varies suboptimally across different engine conditions
Solution Approach 1:
The patent implements feedback control by measuring exhaust gas flow rate and using this information to adjust reductant injection pressure. The system continuously monitors operating conditions and modifies injection pressure accordingly, ensuring optimal mixing efficiency across varying engine conditions while maintaining relatively simple system architecture.
Solution Approach 2:
The system transitions from a static fixed-pressure injection system to a dynamic variable-pressure system. By making injection pressure adaptable to real-time exhaust flow conditions, the system achieves consistent mixing efficiency across different operating regimes without requiring complex hardware modifications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables better mixing and distribution of the reductant with exhaust gas, reduces deposits, and maintains optimal catalytic conversion efficiency across varying engine conditions, improving the overall performance of the aftertreatment system.
Implementation Method 1
A reductant insertion assembly is fluidly coupled to the reductant storage tank and the SCR system. The controller is configured to determine a first pressure at which the reductant is to be delivered to the selective catalytic reduction system and adjust an operating parameter of the reductant insertion assembly.
Implementation Method 2
a selective catalytic reduction (SCR) catalyst to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3)
Implementation Method 3
an exhaust reductant, (e.g., a diesel exhaust fluid such as urea) is injected into the aftertreatment system to provide a source of ammonia, and mixed with the exhaust gas to partially reduce the NOx gases
Data Source
AI summary
An aftertreatment system comprises a reductant storage tank and a SCR system including a catalyst for reducing constituents of an exhaust gas. A reductant insertion assembly is fluidly coupled to the reductant storage tank and the SCR system. A controller is communicatively coupled to the reductant insertion assembly. The controller is configured to: determine an initial pressure of the reductant, determine a first pressure at which the reductant is to be delivered to the selective catalytic reduction system and adjust an operating parameter of the reductant insertion assembly. The adjustment of the operating parameter results in an at least selective delivery of the reductant at the first pressure to the SCR system.